Lunar Science Workshop

Light posting because I decided at the last minute to fly up to San Jose for the workshop at NASA Ames. Been listening to lunar stuff all day. Highlight: a talk by Jack Schmitt, the only geologist to walk on the moon, and the second to last to walk on it, a little over 45 years ago. And with the death of John Young a few days ago, only one of five remaining moon walkers. He’s looking pretty good at 82, and I think he stands a good chance of seeing the next person walk on the moon.

16 thoughts on “Lunar Science Workshop”

  1. Most takes on a Lunar base say it should be located in the polar regions where there is likely ice for ISRU and for fuel for an orbiting propellant depot. Did you happen to get his ideas on that?

    Curious to know from a geologists perspective what he found most remarkable about his time on the moon?

    1. In ultimate sense, the use of the Moon is to make solar energy, a primary energy source.
      Or global solution to the world’s energy needs. A energy source for billions or trillions of people.
      In space one get solar energy 100% of the time, rather than on Earth only getting it for about 25% of the time [and consuming large areas to harvest sunlight].
      Near term, you want to get a energy market in space, which in the beginning will be expense per kW hour, but if you have water, and need rocket fuel, cheap electrical energy in space is about $10 per kW hour [thousands of times more expensive than Earth’s electrical cost] allows cheap rocket fuel.
      If making 100 tons of rocket fuel per year on the Moon, then electrical cost might be about $50 per kW hour, but once get to a need of 1000 tons of rocket fuel on the Moon, one could expect electrical power on the Moon to get around $10 per kw hour. And cost of lunar water should also lower dramatically.
      Once have market for electrical power on the Moon, one will get other electrical markets in space and you provide a demand for water from elsewhere in space. And at that point one even think sending probes to other star system.
      But on the Moon if you have electrical power at $10 per Kw hour you could making solar panels on the Moon. Or when price of electrical is more expensive you begin by shipping from Earth, but demand of electrical power increases and cost of electrical decreases, one has greater market. The power plants you make on the Moon will cost more than cost of making them on Earth [hundreds of times more] but they could be cheaper than shipping them from Earth.
      And at this point in time one is much closer to making SPS from earth use.
      In terms of bases, you want to build them after rocket fuel is first sold on the lunar surface, though if wait a decade, the bases should be a lot cheaper to build and operate- or any nation or company could have lunar “bases”.
      And it seems a purpose of a lunar base is development related to electrical power generation- how to make solar panels on the Moon.
      But also other things like nuclear power- including fusion, and including nuclear rocket engines.
      It seems once electrical power is $10 per kW hour [or less] the Moon will become the place to put research labs- for almost anything.

      Anyways one is needed is exploration of the Moon to determine if and where there is minable lunar water. And if there is, then the Moon becomes a usable destination.
      But if going to have many people in space, you should grow food in space, and Mars seems like good place to grow food in space.
      So NASA should determine if the there is minable lunar water, then explore Mars to determine where you might grow food in space- or someplace to have a town on Mars.

      1. The lunar surface is a poor location for solar energy generation. 2 week on, 2 weeks off, distant from any demand site outside of the immediate area. Geosynchronous orbit is a much better location. The Moon might be a good place to get material for building solar stations.

        1. For structural materials yes. For the solar cells themselves, seems like a handwave. I have to read up on this a bit but what seems missing from lunar sources are the dopants needed to make the semiconductor material needed for solar cells. Silicon may be in abundance but what of gallium or arsenic or selenium or germanium? If this has to be shipped up from Earth that would be a severe drag on a robust electrical market. Earth-based electricity is well under a dollar per kW. Maybe we should run SPS in reverse and beam power out from Earth or GEO?

          1. Dopants are, by definition, only used in very small quantities, so that concern seems pointless.

            Phosphorus and boron are the dopants in silicon PV cell (mostly boron; the boron-doped layer is 1000x thicker than the phosphorus-doped layer). The level of dopants in the silicon is typically well below 1 ppm.

            The “rare” element of greatest concern for PV is silver, used for front contacts. This is likely to be replaced by aluminum or copper as PV production is scaled up though, for cost reasons.

        2. The lunar poles are an excellent location for solar energy generation, continuous sunlight at modest mast heights, and volatiles and other materials available locally to expend the energy on to turn it into useful stuff.

        3. –peter
          January 12, 2018 at 12:47 PM

          The lunar surface is a poor location for solar energy generation. 2 week on, 2 weeks off, distant from any demand site outside of the immediate area. Geosynchronous orbit is a much better location. The Moon might be a good place to get material for building solar stations.–

          You harvest solar energy at lunar poles where there also the water. There sites in lunar polar region where one can get 80% of the time with sunlight. And I can combine sites to get higher percent, ie:
          “This study found that two points only ~8 km from each other along a straight ridge extending from Shackleton Crater at the Lunar South Pole are illuminated a combined ~94% of a lunar year. This is because both points cast shadows upon each other during different times of the lunar year”

          But this mostly about beginning stages, later on one can encircle the polar region to get 100% for a grid power.

          GEO is better location particularly if want space solar energy shipped to Earth, but Moon unlike Earth surface can get solar energy without needing to store electrical power by having a grid in lunar polar regions.
          But as said, Moon would good place to start space solar electrical market and would eventfully lead to space solar electrical market in GEO.
          One “could” fully assemble 100 meter square solar array on the Moon and ship it to GEO [in one piece] this also applies to other large structural components which could used in all of Earth’s orbits.
          So from the Moon one make and service Earth’s SPS solar power network in GEO. Though maybe by that time one is mining material from asteroids.
          Main thing is the moon is a place to start a space solar market and to get to having Earth getting solar energy from Space might take 1/2 century after the beginning mining lunar water and making lunar rocket fuel.

          1. from:

            for the example site shown in Fig.
            1, there is a period of continuous illumination of
            several weeks disrupted only by 3 short darkness
            periods, e.g. of durations below 60 hours. If the
            spacecraft is designed such that it can withstand these
            60 hours in darkness, it will survive during the entire lunar summer. However it will not survive the
            upcoming lunar winter as the darkness periods become
            too long. This long period of near unbroken sunlight is
            termed the longest continuous illumination period,
            even if it contains short nights. ”

            To get continuous you need more one location.
            The moon is tilted about 1 1/2 degree in relation to Sun.
            Or a north or south “arctic circle” is at about 88 1/2 degrees latitude.
            On earth a degree of latitude is about 111 km and on Moon it’s about 30 km, So radius of lunar polar circle is 1.5 times 30 km- about 50 km. Or diameter of 100 km and circumference of circle of about 300 km.
            Or it’s small region with lots of high mountains and deep craters [though such mountains and craters is general characteristic of Moon- or the poles aren’t particularly dramatic or unique in regard to such terrain- though Apollo landings sites were selected to be safer or not an average terrain].

          2. Another aspect about small region is one tend to select the lunar polar circle on the Earth side so as to communicate to Earth. In terms beginning stages lunar operations/missions.

        4. Solar is nice and neat, but it’s not the only way to get power. Temperature on the moon goes from 100 K to 390 K. So you just drill deep enough and use an appropriate fluid to use the moon as a heat sink to drive turbines. This should provide continuous power day and night at any location.

          1. I think the process required to mine lunar water involves a greater “heat sink” potential as compared to a hole in the ground.

            Let’s look at cubic meter of “water ore”- regolith which 10% water and the water ore is at 50 K.
            Specific heat of water ice.
            This chart begins at -100 C
            -100 C 1.389
            0 C is : 2.050 KJ per kg per K
            And quartz sand at 0 C is .830 KJ per kg per K
            Granite: .790 KJ per kg per K
            Melting of water ice: 334 kJ/kg
            Latent heat of evaporation (at 100°C): 2030 kJ/kg

            Say tonne [1000 kg] of lunar dirt and
            100 kg of water at 50 K to to get the water
            need to add 200 K [or more]
            Let’s say lunar dirt takes, .800 per K per kg
            200 times .8 times 1000 kg = 160,000 Kilo joules.

            With 100 kg of water, it has to melt and vaporize.
            Melting is 100 times 334 kJ is 33,400 kilo joules
            Evaporation depends on temperature, but call it 2000:
            100 times 2000 KJ is 200,000 kilo joules.
            And H20 has to warmed by 200 K. let’s say it’s 1.2 KJ
            is 24,000 kilo joules, total is about 260.000 KJ per 100 kg
            raised by 200 K and melted and vaporize in order to get water from the dirt. Plus the dirt isn’t very warm after you heated it: 250 K- or more [ 250 K = -23.15 C].

            Now in terms of heat sink, one uses the cold water ore [dirt and water at 50 K] to cool warm Hydrogen and Oxygen to make cryogenic rocket fuel. Pressurize the gases and use dirt to to cool and liquify, and it terms final stage of making the liquid rocket, the colder the dirt the less electrical energy needed to pressurize and liquify the rocket fuel- and Liquid hydrogen requires most electrical energy. Or “save” the coldest dirt for making LH2.
            But one could use the ore which has had most of the water extracted from it for other heat sink purposes. Or it’s “waste” one might use and possibly extract more water or whatever from it. Or you might heat it the 200 C and giving one “product” which sellable [warmed dirt- is worth something per ton- if say it’s less than $100 per ton, then apparently it’s not worth enough].
            It seems at some point in process, one will want to extract iron, one look at as removing the iron so you don’t have to warm the iron as a part of water ore. So might want us cold iron, less than say 150 K, but separate it at say 200 K. And having ore separated by magnetic process, might ore one heat to much higher temperatures to extract oxygen by using CO or H2.
            But if going to get 100 tons of water per year, one have process 1000 tons and this can used as heat sink.

          2. gbaikie,

            Energy density is a distraction from the main point. The point is energy can be continuously extracted and stored, day or night, from any location on the moon, if you look beyond solar panels.

            The material used as a heat store can be anything as long as it’s insulated. Energy density is just an engineering issue. More important is that the working fluid be efficient at transporting and transmitting heat.

  2. I’ve often wondered how much more we know about the Moon if Schmitt had been the first geologist to walk on the Moon instead of the only. I recall that a lot of the most important specimens were ones he collected.

    Not necessarily more missions, earlier emphasis of the difference between someone that spent his life learning what to look for versus a few hours of briefings among thousands of hours of the same.

  3. Solar thermophotovoltaics may make more sense on the moon.

    This kind of system concentrates sunlight onto a thermal absorber, which then selectively reradiates near IR onto tuned PV cells. The thermal absorber can be integrated with a thermal storage mass, likely using lunar materials.

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